36 Nutrients and harmful algal blooms: general issues and examples from the northern gulf of mexico

Rocky intertidal communities in cold waters on open shores tend to have a stable, predictable makeup worldwide. The structure of the environment, the morphology and life history of species, the economics of species behavior and the dynamics of population changes all contribute to the distribution of species in a given habitat. South East Farallon Island, in the Pacific Ocean off the northern California coast, hosts an intertidal community typical in many ways of other rocky intertidal communities. However, two orders of marine algae one might expect to be there, the Fucales and Laminariales, are unexpectedly uncommon on this island. In this paper some of the possible environmental, morphological and life history factors contributing to and restricting the distribution of marine algae in the intertidal zone on South East Farallon Island are considered.     

福建平潭岛海域底栖贝类物种多样性及其地理分布

海洋底栖贝类是海洋底栖无脊椎动物的重要代表。福建平潭岛地处台湾海峡西岸北部, 是中国大陆距台湾岛最近之处, 其海域内的底栖贝类区系对了解台湾海峡及其附近海域的生态环境和底栖生物地理格局具有重要意义。本文基于对2015-2018年间中山大学国土资源与环境系在平潭岛海域采集的3,346号底栖贝类标本的鉴定, 结合已发表文献整理出了平潭岛海域底栖贝类名录, 并梳理了各物种在中国近海的地理分布类型。结果显示, 本研究所采标本分属58科122属161种, 其中47种为平潭岛海域新记录。结合历史文献记录, 平潭岛海域共有底栖贝类98科244属395种。其中93.7%的种类在南海亦有分布, 82.0%的种类在东海有分布, 31.1%的种类在黄渤海有分布, 42.3%的种类在台湾岛东部海域有分布。南海-东海分布型种类占区系总种数的49.9%; 其次为南海-黄渤海分布型(27.6%)和南海-台湾海峡分布型(16.2%)。分布限于台湾海峡及其以北的种类仅占总种数的6.3%。研究结果表明, 平潭岛海域底栖贝类区系具典型的亚热带性质, 暖水性种类和广温性种类占主要优势, 与南海北部和东海大陆沿岸地区的关系密切, 与台湾岛周边海域的联系相对较弱。     

A long-term comparison of the benthic algal flora of Clare Island, County Mayo, western Ireland

The marine benthic algal flora of Clare Island, off County Mayo, western shore of Ireland, was investigated; collections of intertidal and subtidal marine algae were made at 16 sites along the eastern and southern shores in the years 1990, 1993 and 2000–2002. The data and observations obtained were compared with the results of a similar survey conducted by Arthur Disbrowe Cotton in 1910–1911. Considering the results of the original survey and the new survey together, the marine algal flora of the island currently totals 293 species; 224 species were recorded by Cotton in the original survey, whereas 223 species were identified in the present study. Most species are common to the original and the new list and the main differences are easily explainable; the new survey used SCUBA diving, which allowed the collection of several subtidal species not collected in 1910, and Cotton reported several microscopic green and brown algae, usually difficult to recognise in the field, which were not rediscovered. The most remarkable differences consist in the current presence of some large intertidal brown algae (Bifurcaria bifurcata, Cystoseira foeniculacea and Cystoseira nodicaulis) that were not reported in the survey of 1910. Two algae, Codium fragile subsp. tomentosoides and Asparagopsis armata, were introduced in Europe after the original survey. At present, the benthic algal assemblages of Clare Island still have basically the same structure and distribution as in 1910 and, if compared with other coastal areas of Europe, the intertidal marine environment of Clare Island appears remarkably well conserved.     

Species composition and distribution of algae on the fringing coral reef of Sesoko Island (Ryukyu Archipelago) before and after the natural catastrophe of 1998

The species composition and distribution of marine plants on the fringing reef of Secoko Island were studied before and after the mass coral mortality in 1998. The study showed that changes in the bottom communities that occurred after bleaching of corals were caused by the presumed development of marine plants substituting reef-building corals on the bottom. The number of algal species grew from 211 to 345. The projective cover (PC) of hard substrate with macroalgae increased: in 1998, it was 1–10% in the subtidal zone and 20–50% in the intertidal zone, while in 2002 through 2005, the PC reached 71% in the subtidal and 40–85% in the intertidal zone. It is assumed that the phase of the “plant reef” on Sesoko Island is a temporary event, and that the coral reef can recover within several decades, unless a natural catastrophe occurs again.     

Comparative phylogeography of coastal limpets across a marine disjunction in New Zealand

Cook Strait, which separates the North and South Island of New Zealand, has been a transient, but re-occurring feature of the New Zealand land mass throughout the Pleistocene, maintaining its current width and depth for the past 5000 years. Historic land fragmentation coupled with the complex hydrography of the Greater Cook Strait region has created both biogeographic and phylogeographic disjunctions between the North and South Island in several marine species. Here we use mitochondrial cytochrome b DNA sequences of three endemic intertidal limpets, Cellana ornata, Cellana radians and Cellana flava to assess intraspecific phylogeographic patterns across Cook Strait and to look for interspecific concordance of ecological and evolutionary processes among closely related taxa. We sequenced 328-359 bp in 85-321 individuals from 8-31 populations spanning the biogeographic range of the three species. Intraspecific phylogeographic analyses show moderate to strong genetic discontinuity among North and South Island populations due to allopatric fragmentation. This pattern was broadly concordant across the three species and the observed divergence among this group of intertidal limpets (0.3-2.0%) is similar to that of previously studied subtidal organisms. For each species, divergence time calculations suggest contemporary North and South Island lineages diverged from their respective most recent common ancestor approximately 200 000 to 300 000 years before present (bp), significantly earlier than previous estimates in other coastal marine taxa that arose from a miscalculation of divergence time.     

Contrasting patterns of population structure and demographic history in cryptic species of Bostrychia intricata (Rhodomelaceae,Rhodophyta) from New Zealand

Spatial patterns of genetic diversity provide insight into the demography and history of species. Morphologically similar but genetically distinct “cryptic” species are increasingly being recognized in marine organisms through molecular analyses. Such species are, on closer inspection, often discovered to display contrasting life histories or occasionally minor morphological differences; molecular tools can thus be useful indicators of diversity. Bostrychia intricata, a marine red alga, is widely distributed throughout the Southern Hemisphere and comprises many cryptic species. We used mitochondrial cytochrome c oxidase I gene sequences to assess the genetic variation, population genetic structure, and demographic history of B. intricata in New Zealand. Our results supported the existence of three cryptic species of B. intricata (N2, N4, and N5) in New Zealand. Cryptic species N4, which was found throughout New Zealand, showed a higher genetic diversity and wider distribution than the other two species, which were only found in the North Island and northern South Island. Our analyses showed low to moderate genetic differentiation among eastern North Island populations for cryptic species N2, but high differentiation among North and South Island populations for N4, suggesting different population structure between these cryptic species. Data also indicated that N2 has recently undergone population expansion, probably since the Last Glacial Maximum (LGM), while the higher genetic diversity in N4 populations suggests persistence in situ through the LGM. The contrasting population structures and inferred demographic histories of these species highlight that life history can vary greatly even among morphologically indistinguishable taxa.     

Alternate life history phases of a common seaweed have distinct microbial surface communities

Macroalgal life histories are complex, often involving the alternation of distinct free‐living life history phases that differ in morphology, longevity and ploidy. The surfaces of marine macroalgae support diverse microbial biofilms, yet the degree of microbial variation between alternate phases is unknown. We quantified bacterial (16S rRNA gene) and microeukaryote (18S rRNA gene) communities on the surface of the common intertidal seaweed, Mastocarpus spp., which alternates between gametophyte (foliose, haploid) and sporophyte (encrusting, diploid) life history phases. A large portion (97%) of bacterial taxa on the surface Mastocarpus was also present in samples from the environment, indicating that macroalgal surface communities are largely assembled from the surrounding seawater. Still, changes in the relative abundance of bacterial taxa result in significantly different communities on alternate Mastocarpus life history phases, rocky substrate and seawater at all intertidal elevations. For microeukaryote assemblages, only high intertidal samples had significant differences between life history phases although sporophytes were not different from the rocky substrate at this elevation; gametophytes and sporophytes did not differ in microeukaryote communities in the mid and low zones. By sequencing three host genes, we identified three cryptic species of Mastocarpus in our data set, which co‐occur in the mid‐to‐low intertidal zone. In these samples, M. alaskensis sporophytes harboured distinct bacterial communities compared to M. agardhii and M. intermedius sporophytes, which were not distinguishable. Conversely, microeukaryote communities did not differ among species.     

A subtidal transect in Jervis Bay,New South Wales

Long-term variations in the intertidal algal flora of the entire rock platform at Plantation Point, Jervis Bay, are described by May (1981). The study now reported presents similar long-term changes in the flora of a subtidal region of the same headland, observed within the same period of time. This first detailed report of subtidal macroalgal communities in New South Wales describes a several-year study of the benthic communities along a transect in the upper sublittoral region of a rocky headland at Plantation Point, Jervis Bay. Eighty-nine species of algae were recorded, five of which were previously unrecorded for New South Wales. The area studied is dominated by the large brown algae Ecklonia radiata and Phyllospora comosa, large areas of which were cleared periodically by storms. Turf, shade and crustose coralline algal communities also were present. Storms, seasonal variation and longer term changes all affected the abundance and distribution of the algal species growing along the transect and hence the floristic composition of the area.     

Yeasts of the White Sea intertidal zone and description of Glaciozyma litorale sp. nov.

The intertidal yeast communities inhabiting various environments in the territories of the White Sea Biological Station “Kartesh” (WSBS ZIN RAS) and the N.A. Pertsov White Sea Biological Station (WSBS MSU) were studied. A total of 31 yeast species were isolated using a conventional plating technique and identified using molecular methods. The yeast community of the White Sea intertidal zone consists of members that are typical for marine substrates, ubiquist species that are common in water and in low-temperature terrestrial environments, and a group of species that was isolated from marine substrates for the first time. The most diverse yeast communities formed on the surface of marine algae and in silt. Metschnikowia zobellii, which is a typical inhabitant of northern seas, was the most abundant yeast on algae from both biological stations. A new basidiomycetous yeast species, which was described in this work as Glaciozyma litorale sp. nov., dominated in the silt samples. The type strain of this new species is K94b^T (=KBP 4246^T = VKPM Y-3850^T = PYCC 6252^T = CBS 12957^T = DSM 28204^T); MycoBank registration number is MB 805475.     

Competition, mortality and diversity in South Atlantic coastal boulder communities

Boulder shores are common at all latitudes and dominate the intertidal and subtidal zones of sub-Antarctic coastlines. The encrusting benthos of boulders was examined on similar shore types at four locations: Tierra del Fuego, East Falkland, West Falkland and Bird Island (off South Georgia). Bird Island is unusual in experiencing high trampling and organic enrichment from fur seals. The results were compared to a Patagonian site and a non-trampled South Georgia site (Husvik) and other sites taken from the literature. Principal Component Analysis revealed South Atlantic/Southern Ocean encrusting faunas formed a distinct cluster when compared to assemblages from elsewhere at similar latitudes. Bray Curtis cluster analysis of the South Atlantic-Southern Ocean sites showed the major division was between Southern Ocean and South Atlantic Ocean sites, beyond which there were three distinct clusters centred around Patagonia (Magellanic), the Falklands and Southern Ocean sites. The organisation of competitive interactions between species was mostly determinate and transitive (essentially hierarchical). The transitivity index scores were higher than most similar assemblages studied to date. The diversity of encrusting assemblages ranged from Shannon Weaver H values of 2.38–0.77 (East Falkland and Bird Island, respectively) in the intertidal to 1.27–0.73 (Patagonia and South Georgia, respectively) in the subtidal zone. Annual mortality (of bryozoan colonies) varied from 85–97% in the intertidal to 65–92% in the subtidal, being higher in the Southern Ocean than South Atlantic sites, largely due to ice scour and wave action. The Bird Island mortality values may be high even for a Southern Ocean site. Accepted: 5 October 2000     

An examination of species dispersion patterns along the intertidal gradient on Macquarie Island (sub-Antarctica) using a restricted occupancy model

It has been widely held that intertidal zonation boundaries and the tidal emersion levels are causally related: the critical tidal level hypothesis. In order to evaluate this hypothesis, the dispersion patterns of species boundaries on the intertidal rocky shores of Macquarie Island (sub-Antarctica) were examined using a restricted occupancy model to test the null hypothesis that the observed species were randomly dispersed along the tidal emersion gradient. Subsequently this investigation demonstrated that the intertidal species boundaries on Macquarie Island shores were randomly dispersed with respect to the tidal emersion gradient. Hence no prima facie evidence was found to support the critical tidal level hypothesis. This suggests that tidal emersion is not a significant factor structuring intertidal communities on Macquarie Island.     

Contrasting patterns of genetic structure and phylogeography in the marine agarophytes Gelidiophycus divaricatus and G. freshwateri (Gelidiales,Rhodophyta) from East Asia

The evolutionary and population demographic history of marine red algae in East Asia is poorly understood. Here, we reconstructed the phylogeographies of two upper intertidal species endemic to East Asia, Gelidiophycus divaricatus and G. freshwateri. Phylogenetic and phylogeographic inferences of 393 mitochondrial cox1, 128 plastid rbcL, and 342 nuclear ITS2 sequences were complemented with ecological niche models. Gelidiophycus divaricatus, a southern species adapted to warm water, is characterized by a high genetic diversity and a strong geographical population structure, characteristic of stable population sizes and sudden reduction to recent expansion. In contrast, G. freshwateri, a northern species adapted to cold temperate conditions, is genetically relatively homogeneous with a shallow population structure resulting from steady population growth and recent equilibrium. The overlap zone of the two species roughly matches summer and winter isotherms, indicating that surface seawater temperature is a key feature influencing species range. Unidirectional genetic introgression was detected at two sites on Jeju Island where G. divaricatus was rare while G. freshwateri was common, suggesting the occurrence of asymmetric natural hybrids, a rarely reported event for rhodophytes. Our results illustrate that Quaternary climate oscillations have left strong imprints on the current day genetic structure and highlight the importance of seawater temperature and sea level change in driving speciation in upper intertidal seaweed species.     

泉州湾岩相潮间带底栖生物生态研究Ⅰ.物种多样性与分布特征

2001年11月至2002年8月在泉州湾浮山(R1)、下洋(R2)、垵头(R3)和大坠岛(R4) 选择4条岩相潮间带断面对底栖生物分布进行了调查,共采集了6687号标本.经分析鉴定共有324种,其中有藻类17种,多毛类102种,软体动物96种,节肢动物62种,棘皮动物11种,其他动物共有36种.岩相断面种类的水平分布受制于潮流和海浪,不同断面的种数排序是浮山(206种)＞下洋(197种)＞大坠岛(193种)＞垵头(166种).垂直分布主要受制于潮汐和海浪.各断面不同潮区的共同特征是中潮区的物种最多,在129-156种之间;低潮区居第二,在87-116种之间;高潮区的种类最少,在9-20种之间.种数的季节变化反映生物对水温的适应性,不同季节种数排序为夏季(190种)＞春季(164种)＞秋季(158种)＞冬季(150种).     

Distinct latitudinal community patterns of Arctic marine vertebrates along the East Greenlandic coast detected by environmental DNA

Aim

Greenland is one of the places on Earth where the effects of climate change are most evident. The retreat of sea ice has made East Greenland more accessible for longer periods during the year. East Greenland fjords have been notoriously difficult to study due to their remoteness, dense sea ice conditions and lack of infrastructure. As a result, biological monitoring across latitudinal gradients is scarce in East Greenland and relies on sporadic research cruises and trawl data from commercial vessels. We here aim to investigate the transition in fish and marine mammal communities from South to Northeast Greenland using environmental DNA (eDNA).

Location

South to Northeast Greenland.

Methods

We investigated the transition in fish and marine mammal communities from South to Northeast Greenland using eDNA metabarcoding of seawater samples. We included both surface and mesopelagic samples, collected over approximately 2400 km waterway distance, by sampling from Cape Farewell to Ella Island in August 2021.

Results

We demonstrate a clear transition in biological communities from south to northeast, with detected fish and mammal species matching known distributions. Samples from the southern areas were dominated by capelin (Mallotus villosus) and redfish (Sebastes), whereas northeastern samples were dominated by polar cod (Boreogadus saida), sculpins (Myoxocephalus) and ringed seal (Pusa hispida). We provide newly generated 12S rRNA barcodes from 87 fish species, bringing the public DNA database closer to full taxonomic coverage for Greenlandic fish species for this locus.

Main Conclusions

Our results demonstrate that eDNA sampling can detect latitudinal shifts in marine biological communities of the Arctic region, which can supplement traditional fish surveys in understanding species distributions and community compositions of marine vertebrates. Importantly, sampling of eDNA can be a feasible approach for detecting northward range expansions in remote areas as climate change progresses.     

Composition,diversity and distribution of microbenthos across the intertidal zones of Ryazhkov Island (the White Sea)

The composition and distribution of the main unicellular eukaryotic groups (diatom algae, ciliates, dinoflagellates (DF), other phototrophic (PF) and heterotrophic flagellates (HF)) were investigated in sandy sediments at five stations allocated across the tidal sheltered beach of the White Sea. Overall, 75 diatoms, 98 ciliates, 16 DF, 3 PF and 34 HF species were identified; some are new records for the White Sea. Common species for each group are illustrated. Diatoms and ciliates showed high alpha-diversity (species richness per sample), whereas flagellates were characterized by high beta-diversity (species turnover across the intertidal flat). Each group demonstrated its own spatial pattern that was best matched with its own subset of abiotic variables, reflecting group-specific responses to environmental gradients. Species richness increased from the upper intertidal zone seaward for ciliates but decreased for HF, whereas autotrophs showed a relatively uniform pattern with a slight peak at the mid-intertidal zone. Across the littoral zone, all groups showed distinct compositional changes; however, the position of the boundary between “upper” and “lower” intertidal communities varied among groups. Most of the species found at Ryazhkov Island are known from many other regions worldwide, indicating a wide geographic distribution of microbial eukaryotic species.     

The importance of shore height and host identity for amphipod assemblages

The spatial distribution of organisms associated with marine intertidal macroalgae may be a direct result of their tolerance to air exposure or an indirect consequence of the distribution of their host. We compared amphipod assemblages from five intertidal macroalgae to investigate their relationship with algal identity. To test the effect of height regardless of algal characteristics, we transplanted coralline algal turfs to three different levels within the intertidal zone and compared amphipod assemblages after 1 and 14 days. Interstitial volume was positively correlated to the abundance of amphipods, suggesting that this attribute may correspond better to the potential space for their occupation when compared to algal biomass, thallus volume or the ratio between thallus and interstitial volume. Algal level determined the structure of the amphipod assemblages. Upper-level (Acanthophora spicifera and Caulerpa racemosa) and intermediate-level (coralline) algae host similar amphipod assemblages dominated by Apohyale media, but different from lower-level algae (Padina gymnospora and Sargassum cymosum), which were dominated by Hyale niger. Ten of the 15 amphipod species reported from natural communities were found in the transplanted plots. Distinct pools of amphipod species colonized coralline transplants at upper and lower levels after 1 day. However, regardless of the position on the shore, transplanted coralline turfs supported similar assemblages after 14 days, indicating that algal identity is also important for species assemblages. Our results suggest that both height on the shore and host identity combine to determine the vertical structure of amphipod assemblages in the rocky intertidal.     

52 Beta-dimethylsulfoniopropionate (Dmsp) as a grazing deterrent in coastal phytoplankton communities

One of the most commonly predicted effects of global ocean warming on marine communities is a poleward shift in the distribution of species with an associated replacement of cold-water species by warm-water species. Such predictions are imprecise and based largely on broad correlations in uncontrolled studies that examine changes in species composition and abundance relative to seawater temperature. Before-After-Control-Impact (BACI) analyses of the effects of a large thermal discharge shows that an induced 3.4 deg. C rise in seawater temperature over 10 years along 2 km of rocky coastline resulted in significant community-wide changes in 150 species of algae and invertebrates relative to controls. Contrary to predictions from biogeographic models, there was no trend towards warm-water species with southern geographic affinities replacing cold-species with northern affinities. Instead, communities were greatly altered in apparently cascading responses to changes in abundance of several habitat-forming taxa, particularly subtidal kelps (e.g. Pterygophora californica ) and intertidal foliose red algae (e.g. Mazzaella flaccida ). Many temperature sensitive algae decreased greatly in abundance, whereas many invertebrate grazers increased. The results indicate that the responses of temperate reef communities to ocean warming can be strongly coupled to direct effects on habitat-forming taxa and indirect effects operating through ecological interactions. Given our understanding of temperate reef ecology and its local variability, the results also suggest that accurate predictions of the effects of global ocean warming will be difficult to make.     

Ecological contrasts across an Antarctic land–sea interface

Abstract We report the composition of terrestrial, intertidal and shallow sublittoral faunal communities at sites around Rothera Research Station, Adelaide Island, Antarctic Peninsula. We examined primary hypotheses that the marine environment will have considerably higher species richness, biomass and abundance than the terrestrial, and that both will be greater than that found in the intertidal. We also compared ages and sizes of individuals of selected marine taxa between intertidal and subtidal zones to test the hypothesis that animals in a more stressed environment (intertidal) would be smaller and shorter lived. Species richness of intertidal and subtidal communities was found to be similar, with considerable overlap in composition. However, terrestrial communities showed no overlap with the intertidal, differing from previous reports, particularly from further north on the Antarctic Peninsula and Scotia Arc. Faunal biomass was variable but highest in the sublittoral. While terrestrial communities were depauperate with low biomass they displayed the highest overall abundance, with a mean of over 3 × 10⁵ individuals per square metre. No significant differences in ages of intertidal and subtidal individuals of the same species were found, with bryozoan colonies of up to 4 years of age being present in the intertidal. In contrast with expectation and the limited existing literature we conclude that, while the Antarctic intertidal zone is clearly a suboptimal and highly stressful habitat, its faunal community can be well established and relatively diverse, and is not limited to short‐term opportunists or waifs and strays.     

Impacts and negative feedbacks in community recovery over eight years following removal of habitat-forming macroalgae

The decline or loss of habitat-forming species has affected rocky shore marine communities worldwide. Many short-term studies have documented the initiation of cascading effects due to canopy losses of macroalgae, but relatively few studies have followed recovery dynamics over many years. Here, we show that the experimental removal of a dominant intertidal fucoid in southern New Zealand had numerous community effects up to 8 years later. Even though the dominant fucoid returned to a nearly closed canopy, there remained many differences between disturbed and control communities. The disturbed treatments had lower plant density and biomass of the dominant fucoid, fewer species and more turfing coralline algae than controls. Plots with press disturbances were more affected than those with pulse disturbances. The negative feedback of turfing algae on the recovery of fucoid recruitment resulted in effects on cover and diversity in the wider community being evident after 8 years. We discuss the feedbacks between fucoids, benthic turfing algae and community recovery and argue that if biodiversity impacts on marine rocky reefs are to be understood, the role of non-trophic interactions in structure, function and dynamics must be better delineated.     

51 Characterization of the northwestern gulf of Mexico macroalgae

One of the most commonly predicted effects of global ocean warming on marine communities is a poleward shift in the distribution of species with an associated replacement of cold‐water species by warm‐water species. Such predictions are imprecise and based largely on broad correlations in uncontrolled studies that examine changes in species composition and abundance relative to seawater temperature. Before‐After‐Control‐Impact (BACI) analyses of the effects of a large thermal discharge shows that an induced 3.4 deg. C rise in seawater temperature over 10 years along 2 km of rocky coastline resulted in significant community‐wide changes in 150 species of algae and invertebrates relative to controls. Contrary to predictions from biogeographic models, there was no trend towards warm‐water species with southern geographic affinities replacing cold‐species with northern affinities. Instead, communities were greatly altered in apparently cascading responses to changes in abundance of several habitat‐forming taxa, particularly subtidal kelps (e.g. Pterygophora californica) and intertidal foliose red algae (e.g. Mazzaella flaccida). Many temperature sensitive algae decreased greatly in abundance, whereas many invertebrate grazers increased. The results indicate that the responses of temperate reef communities to ocean warming can be strongly coupled to direct effects on habitat‐forming taxa and indirect effects operating through ecological interactions. Given our understanding of temperate reef ecology and its local variability, the results also suggest that accurate predictions of the effects of global ocean warming will be difficult to make.